1. Field of the Invention
This invention pertains to skin conditioning compositions which comprise relatively high loadings of alpha hydroxy acids in a stabilized, aesthetically pleasing form. Specifically, these compositions are emulsions stabilized by a complex of polyethylene glycol (PEG) and a cationic surfactant.
2. Background of the Prior Art
It is well established that alpha hydroxy acids have a variety of utilities in connection with skin conditioning. Alpha hydroxy acids have been documented in the treatment of a variety of skin conditions having to do with keratinazition, see U.S. Pat. Nos. 5,091,171 and 4,363,815. U.S. Pat. No. 5,618,850 describes problems encountered in connection with use of these acids in skin treatments, including problems resulting from lack of stabilization of the vehicle incorporating them. U.S. Pat. No. 5,616,332 describes the preparation of a variety of cosmetic and pharmacological formulations employing alpha hydroxy acids (AHA's). U.S. Pat. No. 5,621,006 describes the use of certain alpha hydroxy acids and related compounds for topical treatment of a variety of skin disorders.
Although the application of alpha hydroxy acids at significant loadings has been documented as having value in the treatment of skin conditions, as noted, the delivery of these acids to the skin in appropriate amounts is problematical. One particular difficulty encountered is the stabilization of conventional oil-in-water (O/W) emulsions, which, due in part to the acidic nature of the preparation, are unstable, have a relatively short shelf life, and upon storage, tend to develop an aesthetically unpleasant character. Further, to achieve the best possible skin treatment (treatment can broadly encompass addressing specific skin disorders, moisturizing, de-keratinazition, etc.) it is desirable to provide a preparation, such as a lotion or creme, which is resistant to be washed off upon rinsing of the skin. Such compositions are addressed in U.S. Pat. No. 5,013,763, for delivery of agents other than alpha hydroxy acids. Other formulations are described in U.S. Pat. No. 4,389,418.
Other skin conditioning active agents are known. As one example, various oatmeal preparations, oatmeal extracts and the like, are known to provide a soothing skin effect. The delivery of oatmeal in a stable O/W emulsion itself presents stability problems.
Accordingly, it remains an object of those of ordinary skill in the art to provide a skin conditioning treatment, an O/W emulsion, which is stable, is a suitable carrier for one or more AHA, is a suitable carrier for topically active agents such as sunscreens, and the like.